PreK–6.

The program came about thanks to Mark Collin, who spent eight years working as a school counseling psychologist in a rural district in Northern California. He noticed that children lacked an emotional vocabulary and coping strategies, and — drawing on his earlier experience as a carpenter — proposed the metaphor of a personal toolbox. Together with his students, he gradually identified and named 12 such "tools"; over time this practice developed into a full written program that other schools began to adopt.

The program is built on the metaphor of tools: it assumes that the skills a child needs are already present within them, and the task is simply to teach them to consciously reach for the right "tool" in a given situation. The program gives children a shared, understandable language and practices for self-regulation, empathy, building relationships, and overcoming difficult life situations, including those tied to traumatic experiences.

The program relies on a set of materials at different levels: a foundational guide with the program's philosophy and principles (Essential Toolbox Guide, K–6), separate detailed lesson plans for grades K–3 and 4–6, and "Circle of Friends." Implementation begins with training for educators: an introductory course, "Phase I" (2.5 hours, introducing tools 1–7), followed by "Phase II" (2.5 hours, tools 8–12 and deeper work with the program).

More than 265,000 students worldwide are currently using the program (per the official website): reach spans 200 cities across 38 U.S. states, with more than 12,000 educators trained.

38 U.S. states, as well as Canada, Costa Rica, Peru, South Africa, Ghana, France, Germany, Jordan, Australia, and Korea — with inquiries from 25 additional countries.

The program's primary language is English. Materials for students and parents are available in Spanish (some materials are labeled as bilingual, English-Spanish).

The program is included in the CASEL Program Guide registry with a status of Promising.

A quasi-experimental study from the 2015–2016 school year (published in 2023) covered 1,766 K–2 students at an urban school in the western United States. Program participants showed improved social-emotional competencies and coping strategies compared with the control group — an effect recorded eight weeks after the study began, adjusted for sex, age, ethnicity, English-learner status, and other factors.